The goal of this project is to investigate cellular "immune responses of cells comprising the muccosal follicles that line thew gastrointestinal tract forming the gut associated lymporeticular tissue" (GALT), and is responsive to the program announcement PAS-98-040, "Opportunities in AIDS Research Program: Human Immunology. GALT is a major site for viral replication, and understanding local immune and their relationship to systemic responses will be crucial in mobilization of cells for immune reconstitution and in vaccine studies. In the first specific aim the will isolate mononuclear cells from GALT biopsies in peripheral blood. In the second specific aim, they will track HIV-1 specific CTL in GALT and peripheral blood. The investigators believe that the proposed studies will contribute considerably to our understanding of HIV-1 specific immune responses in gut associated lymphoreticular tissue.